1. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to sensors used for sensing physiological parameters of a patient.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient.
Pulse oximeters typically utilize a non-invasive sensor that is placed on or against a patient's tissue that is well perfused with blood, such as a patient's finger, toe, forehead or earlobe. The pulse oximeter sensor emits light and photoelectrically senses the absorption and/or scattering of the light after passage through the perfused tissue. The data collected by the sensor may then be used to calculate one or more of the above physiological characteristics based upon the absorption or scattering of the light. More specifically, the emitted light is typically selected to be of one or more wavelengths that are absorbed or scattered in an amount related to the presence of oxygenated versus de-oxygenated hemoglobin in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of the oxygen in the tissue using various algorithms.
In many instances, it may be desirable to employ, for cost and/or convenience, a pulse oximeter sensor that is secured with adhesives and is reusable. To facilitate this requirement, pulse oximeters may be assembled by wrapping a sensor in a flexible material. The wrapped sensor may then be secured to a cover material that is used to affix the wrapped sensor to the patient. Finally a packaging film may be applied over the adhesive and cover materials to protect the adhesive portion prior to the application of the sensor to the patient.
Such adhesive and reusable sensors, however, may be subject to stresses during unpackaging, application, and use. For example, when the film covering of an oximetry sensor, such as a neonate sensor, is removed before application, the force of pulling away the film from the adhesive may cause stresses in the flexible material that cause the flexible material to tear. Tears in the flexible wrapping material may expose portions of the pulse oximeter sensor's circuitry and decrease the sensor's performance. These tears may be more common in corners of the flexible material where the stresses of pulling on the sensor are at their highest. As a further example, after the sensor is attached to the patient, stresses due to movement of the patient or the sensor may also lead to tears in the flexible material.
Also, it is desirable that the pulse oximeter sensor be assembled in a manner that eliminates exposure of the sensor's circuitry. Exposure of the sensor circuitry may lead to apprehension by the end user, and exposed circuitry may be susceptible to external sources of interference that may decrease the performance of the sensor. Therefore, the reusable sensor should be assembled in a manner that provides for complete enclosure of the pulse oximeter's circuitry. For example, when a pulse oximeter is assembled, the flexible material wrapped around the sensor should cover all portions of the pulse oximeter sensor. More specifically, when the flexible material is wrapped around the sensor, corner regions should not be void of material due to folds into adjacent areas.